CD16-158-VALINE CHIMERIC RECEPTOR T CELLS OVERCOME THE RESISTANCE OF KRAS-MUTATED COLORECTAL CARCINOMA CELLS TO CETUXIMAB

Abstract

KRAS mutation hinders the therapeutic efficacy of epidermal-growth-factor-receptor (EGFR) mAb (cetuximab and panitumumab)-based immunotherapy of EGFR+ cancers. Although, cetuximab controls KRAS-mutated cancer cell growth in vitro utilizing a NK cell-mediated antibody-dependent-cellular-cytotoxicity-(ADCC) mechanism, KRAS-mutated colorectal carcinoma (CRC) cells can still escape NK cell immunosurveillance. To overcome this limitation, we used cetuximab and panitumumab to redirect Fc{gamma} chimeric receptor (CR) T cells against KRAS-mutated HCT116 CRC cells. We compared 4 polymorphic Fc{gamma}-CR constructs including CD16158F-CR, CD16158V-CR, CD32131H-CR, and CD32131R-CR which were transduced into T cells utilizing retroviral transduction. Percentages of transduced T cells expressing CD32131H-CR (83.5{+/-}9.5) and CD32131R-CR (77.7.{+/-}13.2) were significantly higher than those expressing with CD16158F-CR (30.3{+/-}10.2) and CD16158V-CR (51.7{+/-}13.7) (p<0.003). CD32131R-CR T cells specifically bound soluble cetuximab and panitumumab. However, only CD16158V-CR T cells released significantly higher levels of interferon gamma (IFN{gamma}=1145.5 pg/ml {+/-}16.5 pg/ml, p<0.001) and tumor necrosis factor alpha (TNF=614 pg/ml {+/-} 21 pg/ml, p<0.001) than non-transduced T cells when incubated with KRAS-mutated HCT116 cells opsonized with cetuximab. Only CD16158V-CR T cells combined with cetuximab controlled the growth of HCT116 cells subcutaneously engrafted in CB17-SCID mice. These results suggest that CD16158V-CR T cells combined with cetuximab represent useful reagents to develop an effective immunotherapy of EGFR+KRAS-mutated cancer.